Smoking through a water pipe is considered less harmful than smoking cigarettes, as toxic components of tobacco are thought to be filtered out by the water.

Mohammad Hossein Boskabady, Mashhad University of Medical Sciences (MUMS), Iran, and colleagues compared lung function and respiratory symptoms among 57 water pipe smokers, 30 deep (S-DI) and 51 normal inhalation cigarette smokers (S-NI), and 44 non-smokers.
Results showed an increased prevalence and severity of respiratory symptoms among water pipe smokers and cigarette smokers.
Wheezing was present in 23 % of water pipe smokers, 30 % in S-DI, and 21.6 % in S-NI. Chest tightness was present in 36.8 % of water pipe smokers, 40 % in S-DI, and 29.4 % in S-NI. Cough was present in 21 % of water pipe smokers, 36.7 % of S-DI, and 19.6 % of S-NI. Wheezing, chest tightness, and cough only occurred in non-smokers 9.1, 13.3, and 6.8 %, respectively.

• Comparison of pulmonary function and respiratory symptoms in water pipe and cigarette smokers,
  Mohammad Hossein Boskabady, Lila Farhang, Mahbobeh Mahmodinia, Morteza Boskabady, Gholam Reza Heydari,
  Respirology 2012.
  DOI: 10.1111/j.1440-1843.2012.02194.x